This is an update to the Target constraints on:

> 022:08:40.80 +45:44:32.00 ACIS-S/HETG	100.00	AR LAC (HD 210334) CLAUDE CANIZARES	01	01200041


The HETGS AR Lac observation of 100 ks is to be split into 6
phase-critical exposures as follows:

                          texp        phase     phase tolerance
                          [ks]      min   max    min     max
  1 - primary eclipse     35       0.898 0.102   0.022	0.022
  2 - primary eclipse     35       0.898 0.102   0.022	0.022
  3 - quadrature 1        7.5      0.228 0.272   0.08   0.08
  4 - quadrature 2        7.5      0.728 0.772   0.08   0.08
  5 - quadrature 1        7.5      0.228 0.272   0.08   0.08
  6 - quadrature 2        7.5      0.728 0.772   0.08   0.08

Observations should preferably be made within 2-4 consecutive orbits. 

Use the updated ephemeris: MJD 48501.1232  + 1.98318E.


I would like to specify 

 "Multi-Telescope Observations?" = "Y"
 "Telescopes"= "Ground".  

This constrains the observations to roughly June 15-Oct 15 1999,
during which time AR Lac is continuously visible with AXAF.

To avoid other x-ray sources in the field, as determined from a PSPC
image and the Observation Visualizer, acceptable roll ranges are:

	105-130, 170-250 degrees.